Use In Particle Physics Experiments Research Articles

Novel large aperture EBCCD

A novel large aperture electron bombardment charge coupled device (EBCCD) has been developed. The diameter of its photocathode is 10 cm and it is the first EBCCD with such a large aperture. Its gain shows good linearity as a function of applied voltage up to −12 kV, where the gain is 2400. The spatial resolution was measured using ladder pattern charts. It is better than 2 line pairs/mm, which corresponds to 3.5 times the CCD pixel size. The spatial resolution was also measured with a copper foil pattern on a fluorescent screen irradiated with X-rays (14 and 18 keV) and a 60 keV gamma-ray from an americium source. The result was consistent with the measurement using ladder pattern charts. The output signal as a function of input light intensity shows better linearity than that of image intensifier tubes (IIT) as expected. We could detect cosmic rays passing through a scintillating fiber block and a plastic scintillator as a demonstration for a practical use in particle physics experiments. This kind of large aperture EBCCD can, for example, be used as an image sensor for a detector with a large number of readout channels and is expected to be additionally applied to other physics experiments.

Characterisation of Vanilla—A novel active pixel sensor for radiation detection

Novel features of a new monolithic active pixel sensor, Vanilla, with 520 × 520 pixels ( 25 μ m square) has been characterised for the first time. Optimisation of the sensor operation was made through variation of frame rates, integration times and on-chip biases and voltages. Features such as flushed reset operation, ROI capturing and readout modes have been fully tested. Stability measurements were performed to test its suitablility for long-term applications. These results suggest the Vanilla sensor—along with bio-medical and space applications—is suitable for use in particle physics experiments.

Aging effects in gas detectors

Degradation of performance of gas detectors under irradiation has been observed since the start of their use in particle physics experiments. In general, the observed damage depends on the amount of radiation seen by the detector but in addition many other parameters like gas composition, gas quality, particle rate and particle type play an extremely important role. The dramatically increased demands in terms of radiation hardness at experiments like HERA-B or those at the LHC have triggered intensive and systematic studies of aging properties of materials, gases and components, resulting in a compilation of a long list of materials which are unusable for high rate experiments, and a selection of materials with acceptable aging properties. Comparisons with results obtained in plasma chemistry have led to an improved understanding of aging phenomena, but due to the large complexity of the processes involved it has until now not been possible to derive recipes which can be generally applied to all high rate applications.

Particle identification in the Time Projection Chamber: MUNU & Gotthard experiments

Time projection chambers have been successfully refined for the use in particle physics experiments. The excellent imaging capability of MUNU and Gotthard experiments encouraged us to further improve this technique. Experimental details, detector performance, event identification, choice of gas, results and future developments of both experiments are discussed.

Blind analysis

We examine what blind analysis is and what motivates its use in particle physics experiments. We explore the methods of blind analysis and give examples of its application in real experiments.(From the workshop ‘Advanced Statistical Techniques in Particle Physics’, 18–22 March 2002)

Investigation of prototype gas-filled photomultipliers

Abstract Parallel-plate gas gain of more than 7000 has been observed in a methane-filled low pressure hexode with a semitransparent photocathode. The photocathode lifetime has been studied in a similarly constructed phototetrode. Conclusions are drawn for the development of future higher gain devices for use in particle physics experiments in high magnetic fields.